Interpretive Summary: Grape berry moth is native to the eastern United States and is a major pest of grapes in vineyard. The larvae directly damage berries throughout the growing season and up to 90% of the berries may be destroyed if vineyards are left unsprayed with pesticides. We have identified and synthesized the key volatiles from grape shoots used by female grape berry moth to locate suitable host plants. Because the traps baited with the synthetic female attractant are more effective in identifying the start of the first flight, the vine growers can use it as an effective tool to accurately monitor the emergence and flight of female moths to determine the emergence of generations and make the timing of management decisions. This information will also be useful to researches and extension specialists developing control strategies for grape berry moth.

Technical Abstract:
Solid-phase microextraction (SPME) and gas chromatography coupled with electroantennographic detection (GC-EAD) were used to identify volatile compounds from shoots of riverbank grape (Vitis riparia) acting as behavioral attractants for female grape berry moth (GBM, Paralobesia viteana). Consistent EAD activity was obtained for 11 chemicals: (Z) 3-hexen-1-yl acetate, (E)-linalool oxide, (Z)-linalool oxide, nonanal, linalool, (E)-4,8-dimethyl 1,3,7-nonatriene, methyl salicylate, decanal, ß-caryophyllene, germacrene-D and a-farnesene. In flight tunnel tests involving mated female GBM and rubber septa loaded with subsets of these 11 compounds, we found that both the 11-component blend and a 7-component blend composed of (E)-linalool oxide, (Z)-linalool oxide, nonanal, (E)-4,8-dimethyl-1,3,7-nonatriene, decanal, ß- caryophyllene and germacrene-D elicited equivalent levels of upwind flight as freshly cut grape shoots. Removing any of these seven compounds singly from the 7-component blend resulted in significant loss of female upwind flight response. In a field trial involving these two synthetic blends, traps equipped with either blend successfully captured more female GBM compared to traps baited with hexane only (control). However, there were no differences in the number of males captured among treatments and the number of females captured was relatively low. Although in flight tunnel trials moths readily made upwind flight to both grape shoots and rubber septa loaded with the best lures, they readily landed on shoots but not on rubber septa. Coupled with relatively low capture rates in the field, this suggests that additional host finding cues need to be explored to improve trap efficacy.